The present invention relates to a color image reading device, an output controller for an image capture system, and a method of controlling an output from a color image reading device. More specifically, the invention relates to the optimization of the positioning of multiple-array linear charge-coupled devices (CCD) to provide improved signal to noise ratio for the scanning of two-dimensional objects, as in document scanners.
A color image reading device such as a linear color charge-coupled device (CCD) may be comprised of an array of linear sensors. Each of the linear sensors are optimized to receive a different portion of a spectral emission from an object imaged on the device. In conventional color CCD devices, each of the linear sensors may include a different color filter and each sensor is separated from an adjacent sensor by a distance of N lines. This results in each array capturing a different line of the document during one raster scan. In conventional arrangements, one of the linear sensors of the array of sensors may be less sensitive to spectral emission. As an example, the signal-to-noise ratio (S/N) for the blue channel or filter in CCD devices may be lower than desired due to the lower sensitivity of the CCD to blue light, and/or lower object illumination levels in the blue portion of the spectrum. Also, because of the CCD line offset as noted above, a single raster from the CCD will contain information from three separate lines. To properly register and display an image, the data of the image must be re-phased to place data from a single line of the image into the same raster of image data.
The present invention provides for an arrangement which overcomes the drawbacks noted above. A first feature of the present invention relates to the reversal of the orientation of the color image reading device relative to an object to be imaged upon it, in order to optimize illumination in blue wavelengths. Because the individual line sensors of the color image reading device are physically offset from one another, that offset results in each sensor capturing a different segment of the object during each raster. When it is desirable to reverse the orientation of the color image reading device relative to the object to be scanned in order to optimize illumination and signal-to-noise ratio, pixel data for each line is then generated in reverse order. In a further feature of the present invention, the altered data from the offset linear sensors are phased based on the reversed orientation noted above.
The present invention provides for a method and means by which to compensate order and phasing of the output from a color image reading device, such as a color image scanning system, that arises from the relative orientation of multiple linear sensor arrays, which involves orienting the color image reading device relative to an object to be scanned by means of a line controller.
The present invention relates to a color image reading device which comprises an array of linear sensors, with each of the linear sensors receiving a different portion of a spectral emission from an object to be imaged. One of the linear sensors of the array of linear sensors being least sensitive to spectral emission and being positioned closest to an illumination source for the object.
The present invention further relates to a color image reading device which comprises an array of linear sensors, with each of the linear sensors receiving a different portion of a spectral emission from an object to be imaged. One of the linear sensors of the array of linear sensors receiving a portion of a spectral emission that is weakest and being positioned closest to an illumination source for the object.
The present invention further relates to an output controller for an image capture system which comprises a color image reading device having an array of linear sensors that receive a different portion of a spectral emission from an object to be. An orientation of the linear sensors resulting in a reversal of pixel data within a raster. The controller of the present invention further comprises a line controller that receives the pixel data from the color image reading device and reverses the pixel data.
The present invention further relates to an output controller for an image capture system which comprises a color image reading device having an array of linear sensors which receive a different portion of a spectral emission from an object to be imaged and provides an image signal indicative thereof. The image signal comprises a raster of pixel data from different points on the object. The controller further comprises a line controller which receives the image signal from the color image reading device and re-phases color pixel values of the raster of pixel data to refer to the same point on the object.
The present invention further relates to a method of controlling an output from a color image reading device which comprises the steps of passing an object to be read relative to a color image reading device having an array of linear sensors, so as to provide for a raster of pixel data representative of different points on the object; and providing the raster of pixel data to a line controller which reverses the raster of pixel data.
The present invention further relates to a method of controlling an output from a color image reading device which comprises the steps of passing an object to be read relative to a color image reading device having an array of linear sensors, so as to provide for a raster of pixel data representative of different points on the object; and providing the raster of pixel data to a line controller which re-phases color pixel values of the raster of pixel data to refer to the same point on the object.